#include <cstdio>

const int N = 1e3 + 5;
int w, b;
double f[N][N];

int main() {
#ifndef ONLINE_JUDGE
#ifdef LOCAL
  freopen("testdata.in", "r", stdin);
  freopen("testdata.out", "w", stdout);
#else
  freopen("CF148D Bag of mice.in", "r", stdin);
  freopen("CF148D Bag of mice.out", "w", stdout);
#endif
#endif

  scanf("%d%d", &w, &b);
  for (int i = 1; i <= w; ++i)
    for (int j = 0; j <= b; ++j) {
      f[i][j] = 1.0 * i / (i + j);
      if (j > 1)
        f[i][j] +=
            f[i - 1][j - 2] * j / (i + j) * (j - 1) / (i + j - 1) * i / (i + j - 2);
      if (j > 2)
        f[i][j] +=
            f[i][j - 3] * j / (i + j) * (j - 1) / (i + j - 1) * (j - 2) / (i + j - 2);
    }
  printf("%.9lf", f[w][b]);
  return 0;
}